HR: 1330h
AN: AE22A-1115    [PDF]
TI: An Electric-Field Meter With Reciprocating Shuter, Used as a Lightning Flash Counter
AU: * Bogoev, I
EM: ivan@campbellsci.com
AF: Campbell Scientific, Inc., 815 West 1800 North, Logan, UT 84321 United States
AU: Byerley, L G
EM: byerley@therive.com
AF: Lightning Protection Technology, 2744 E 5th St, Tucson, AZ 85716 United States
AU: Swenson, J
EM: jswenson@campbellsci.com
AF: Campbell Scientific, Inc., 815 West 1800 North, Logan, UT 84321 United States
AU: Hinckley, A
EM: ahinckley@campbellsci.com
AF: Campbell Scientific, Inc., 815 West 1800 North, Logan, UT 84321 United States
AU: Beasley, W H
EM: whb@ou.edu
AF: School of Meteorology, University of Oklahoma, Norman, OK 73019 United States
AB: Cloud-to-ground (CG) lightning flashes result in transfers of charge from cloud to ground. Consequently, there are relatively large and abrupt changes in the electrostatic field in the region near the ground-strike point. Although cloud (IC) discharges can also result in changes in the electrostatic field at the ground, the changes tend to be smaller. In both cases there will be abrupt step changes in the electric-field record, followed by a characteristic relaxation period. Thus electric-field meters normally used to measure the ambient electrostatic field can also be used to count flashes by counting the abrupt changes. The Campbell Scientific CS110 electric-field meter is especially well suited to the task of monitoring and counting local lightning field changes because of its unique design and special features, including built-in data-processing capability. Because it has a reciprocating shutter under microprocessor control, rather than a spinning rotor, the CS110 has several advantages over traditional field mills, including greater reliability, lower noise, continuous adjustment for drift, and, not least, the option of leaving the shutter open so that the instrument can be operated as a field-change meter sensitive to distant lightning. In this paper we discuss use of the CS110 in field-meter mode to count nearby lightning flashes and in field-change-meter mode to count distant lightning flashes. To test the use of the CS110 as a flash counter for nearby lightning, we calculated the time derivative of the field at each sample; a moving median, M, of the derivatives; a moving standard deviation, s and moving Low and High limits, LH = M + ns, and LL = M - ns, (where n is chosen empirically). Events that exceed the limits are counted as nearby lightning flashes, where the meaning of "nearby" depends on the choice of n. To test the use of the CS110 as a flash counter for distant lightning, we operated it with the shutter open and recorded the output of the charge amplifier directly. We compare the resulting waveforms with those of a standard flat-plate type of field-change antenna.
DE: 3304 Atmospheric electricity
DE: 3324 Lightning
DE: 3360 Remote sensing
DE: 3394 Instruments and techniques
SC: Atmospheric and Space Electricity [AE]
MN: 2003 Fall Meeting